Apparatus for treating liquids with gases



Sept. 7 1926. 1,598,858

W. E. GREENAWALT APPARATUS FOR TREATING LIQUIDS WITH GASES Filed April2, 1923 3 Sheets-Sheet l 000 090 000 900. 08980 08080 0 0 (D 0 0 0 (52:.0 0 0 0 0 0 0 0 O 0 o o 7 3 0 0 0 0 0000000 09 0 0 9 0 0 00 Q hfi 1a n)1c d 1 12 12 12 12 FIG-1 L FIG 3 1 F1 c fjf f Sept. 7, 1926.

w. E; GREENAWALT APPARA'ms' FOR TREATING LIQUIDS WITH GASES Filed April2, 19 23 3 Sheets-Sheet 2 .FIGS) FIG 10 LEE I Q) I ,1

I NVENTOR Sept. 7 1926. 1,598,858 I W. E. GREENAWALT APPARATUS FORTREATING LIQUIDS WITH GASES Filed April 2, 1923 3 Sheets-Sheet 3 FIG 152 Han I NVENTOR pasta Sept. 7, 192

UNITED STATES WILLIAM E. enn mawnn'r, or nnnvnn, coLonA'no.

APPARATUS FOR TREATING LIQUIDS WITH GASES.

Application filed April 2,

The invention has as its object the efi'ective atomization, or finesubdivision, of gas.

in liquid. It finds efi'ective application in the flotation treatment ofores; in the pneumatic agitation of liquids and ore pulps; and theapplication of corrosive gases, such as sulphur dioxide or chlorine, tothe, treatment of copper, gold, and silver ores.

The descript on of the invention will be more particularly directed tothe flotation treatment of ores.

In the flotation treatment of ores, excellent results have been obtainedby applyin "the air, or gas, to the ore pulp, through porous material inthe lower portion of the tank containing the ore pulp. In doing this,certain difiiculties have arisen; among which may be mentioned thedelicate nature of the porous material if it is made of woven fabric,the clogging of the pores ifv inorganic porous-material is used, and thesettlingwof the sands on the porous material and consequent unequaldistribution of the air in worn or clogged porous material.

To overcome these difiiculties, jets of air have been injected into theliquid and the impingement of the air against the liquid 'siibdividesthe air and gives encouraging results," althou h these results are farfrom being as satis actory as theoretical conditions would indicate.

' I have found that if jets of air, or gas,

are mixed with the liquid, and the mixture is injected into thesurrounding liquid in the tank, a very satisfactory atomization can beaccomplished, especially if these jets of "as and liquid are directedagainst one anther, or arranged to inter-penetrate one.

another in the liquid in the tank. It has been found, b this.arrangement, that the injecting of t e gas, in this way, can be made,sufliciently energetic to prevent sands from settling, even in flatbottom tanks, and that the construction of the apparatus can be made inlarge units, which 'has an imr portant bearing in: the practical andeco-.

nomic operation. In the treatment of ores with acid solutions or withcorrosive gases the ore pulp may betreat'ed and agitate by means orairor other tga's by making the gas difl'using members 0 some acidproof, or acid resistin material, such as antimonial lead, or ferrosiicon.

Theadvantage of getting a fine atomiza- I tion of the gas, without aporous material,

is evident.

1923. Serial No. 629.362.

The invention will now be described in detail, reference being made tothe accompanying drawings, in which Fig. 1, represents a plan of theapparatus as applied to the flotation treatment or ores; Fig. 2 thecorresponding longitudinal section; Fig. 3 the corresponding transversesection; Fig. 4: a longitudinal section'of the invention adapted totreat liquids with corrosive ases; Fig. 5 a detail in vertical sectionof t e, at-

omizer, injector, or gas impregnator, and

Fig. 6 the corresponding horizontal section on the line 66 of Fig. 5;Fig. 7 a detail vertical section of a modified form of atomizer, orinjector, and Fig. 8 the correspond- 'i-ng horizontal section on theline 88 of n Fig. 7.; Fig. 9 a detail of the bottom of the tank similarto that shown in Fig. 3; Fig. 10 a cross section of a modification ofthe apparatus as applied to the flotation treatment of ores; Fig. 11 adetail in vertical sec-.

tion of the corresponding atomizer and low-' er portion of the tank;Fig. 12 a cross sectionin detail of the atomizer or injector; Fig. 13 alongitudinal section of a modified apparatus; Fig. 1 4.- a horizontalsection of one end of Fig. 13; Fig. 15 a detail in vertical sectionshowing the relation of the atomizers to the tank; Fig. 16 amodification of the invention, in vertical section, as applied to roundtanks; and Fig. 17 is a vertical section of a modification of theinvention as applied to a continuous flow of gas and liquid in whichboth the gas and liquid are under super-atmospheric ressure.

Referring to the drawings; 1 is a tank adapted to contain the liquid, orore slud e,

to.be treated. The tank is preferably i.-

vided into sections 1, 1 1, and 1, by the vertical partitions 2, so thatthe liquid may fiow progressively throu h the tank from one section tothe next, or any number of sections; for this purpose the partitionshave communicating openings 2, which are intended 'to be large enough tomaintain practically the same liquid level in all the sections composinthe tank. The tank is provided with a liquid inlet 3, with a weiroverflow, outlet 4, and with ,an underfiow' outlet 5 to take the heavierparticles of insoluble "matter which cannot be rejected through the weiroverflow outlet 4. The underflow outlet 5 has a regulating valve, bymeans of which a small ste'ady'stream can be made to flow through theunderflow outlet to take care of the heavier particles of suspendedmatter, while the liquid and slimes overfiou over the weir, and thisweir is made abundantly large so that any irregularity in the feed willnotcause an apprefiiable change in the liquid level in the tan i In thebottom of the tank, in the respective compartments, are gas chambers .6,which are supplied with gas under pressure through the gas pipe 7, andthe flow of gas into the respective gas chambers may-be regulated by thevalves 10. The flow through the gas main 7 may be regulated by the valve11. Communicating with each of the gas chambers 6 are atomizers, gasdistributors, or injectors, 9, arranged and designed so that the gas inthe gas chambers 6 is forced out through discharge passages, and inbeing forced out, acts as an injector, to suck some of the liquid in thetank into the interior of the atomizer, where the gas and liquid aremixed, and the mixture or gas and liquid is then ejected into thesurrounding liquid in the tank. The gas ejected in this way is broughtinto a very fine state of subdivision, or atomization; much finer thanis obtainable by merely'ejecting liquid, offers, it is believed, idealconditions a stream of gas alone into the liquid.- The impetusof theliquid'mixed with the ejected gas carries the gas a comparatively longdistance from the ejector, and by arrangeing-these 'ejectors so that thestreams ofthe mixture of gas and liquid impinge, intersect, or penetrateone another, a fairly fine and uniform distribution of the gas may bemade all over the bottom of the tank, and the finely divided gas,ascending through the for flotation, for impregnation, and for heatingand cooling of the liquid, without the ,use of rotary mechanism.

The gas atomizers may be described in detail by referring to Figs. 5 and6. The compressed gas from the submerged gas chamber 6, is forcedthrough the .pipe 16- intothe gas discharge passages 17, and throughthegas discharge passages 17 into the gas and .liquid'discharge passages19. As the gas is injected from the discharge passage 17 into thedischarge passage 19, it sucks liquid from the tank into the interior ofthe atomizer, through the ducts 18, working somewhat like an injector,and the mixture of gas and liquid is then ejected into the surroundingliquid in the tank, Any number of these atomizers may be screwed intothe gas chamber in-the bottom .of the tank, and they are preferablyarranged sothat radiating jets, orstreams, of gas and liquid, mix,impinge, and penetrate, so as to bring the gas in a fine state ofsubdivision, give a fairly uniform distribution of the gas, and preventviolent surging of the liquid. Violent surging off the liquid isdetrimental to flotation.

treated the jets may be quite fine and quite.

numerous, for, in that case there is no danger of the atomizers becomingclogged :or of sand settling in the ,bottom of the tank. If the-materialto be treated is ore pulp, the jets of gas and liquid should be largerand stronger, at least strong enough to prevent any settling of sands.-The pressure under which the gas should be delivered vto the gas chamberwill also depend largely on the material to be treated. For the sake ofeconomy the gas should be delivered at the lowest pressure which willgive the desired atomization and agitation. In Figs. 7 and 8 is shown amodification of the atomizer shown in Figs. 5 and 6. The gas isdelivered into the interior of the atomizer through the pipe 20, and isejected through a multiplicity of ducts, or discharge passages, 21 intothe general channel formed by the upper and lower plates. This generalchannel is designated by 22. and 23. The stream of gas and liquid isejected outwardly around the entire periphery of the atomizer. In thistype of atomizer, as also in the other type, the gas may be introduceddirectly into the interior of each atomizer, through the pipe 20, andthe fiow of gas to each atomizer may be under direct "control by a valve(not shown). The atomizer may rest directly on the bottom of the tank.This type of atomizer is preferred where violent agitation isrequired inthe presence of corrosive gases or corrosive liquids, or for theagitation of ore pulp containing rather coarse 9 inlet pipe 7 connectedwith the gas chamber .6 through the top instead of through the bottom.Such an arrangement as shown nv 1 Fig. 9, will avoid any complicationsdue to making connections t rough thetank. The gas chambers, as shown inFig. 9, can be raised and lowered, with the atomizers attached, and thusrepairs and inspections can easily b made. I

In Fig. 4, the gas upper portion of the tank and forced 1n the lowerportion by means of the exhausters 30, and both the gas and the materialbeing treated are flowed progressively'from one section to the nextthrough the tank. The gas inlet is shownby 31 and the excess isexhaustedfronidahe gas outlet by 32. This type of apparatus can beconstructed in very large units. A tank, for example, 15 feet wide, 20feet deep, and, 100 feet long, would treat from 2400 tons to 4800 tonsof ore per day of 24 hours, with the time of treatment of one and twohours respectively. This is made possible on the basis that a flatbottom tank can be used, and that settling of the ore particlescan beavoided by the means described, and

that the flow of ore pulp can be made progressively from the, tank inletto the -tank outlets I Fig, 10 shows a modification of the invention, asapplied to flotation, in which two atomizers are placed at the sides ofthe tank in opposite relation, so that thestreams of gas and liquidimpinge, or intersect, or penetrate, one another, and so that the gas isprojected from one side of the tank against the other side. Betterresults are usually obtained if a grating, or perforated member,is'placed above the gas streams in the lower portion of the tank.This'somewhat confines thesphere of action, with the result that the gasparticles are more minutely subdivided, or atomized, and with theadditional advantage that surging iseither avoided or greatly reduced.The grating is shown by 29, the atomizer by 24 and the gas supply pipeby 25.

A detail section of the lower portion of the tank is shown in Fig. '11.The gas is introduced under pressure into the injector, or atomizer, 24through the gas supply pipe 25, and is ejected through the gas dischargepipe, or nozzle, 28, into the discharge passage 27. In doing this, someof the liquid of the tank is sucked into the atomizer through the ducts2'6, and is ejected with the gas. The impetus given tothe stream of gasand liquid ejected from the atomizer, by the gas-pressure in,the ipe 25,carriesthe stream of gas and liquid to the other side of the tank, whileat the same time small gas bubbles are diffused through the entire lowerportion 'of the tank. The streams, impinging, or penetrating, oneanother, greatly assists in'thel diffusion of the indicates the gasdischarge passage and 26' gas bubbles. Y

The atomizers'are intended to be fairly close together, on each sideof,the tank, so as to give a uniform distribution of the gashorliizontally, in the lower portiono'f the tan i Fig. 12, shows adetail section through the atomizer on the line 1212 of Fig. 11. 28

the liquid inlet ducts.

In theflotation treatment of ores, it is vdesirable to have a somewhatquiet zone 12 (Figs. 3 and-10). This is formed by baflles 13 and theprojections 14, so arranged that the .mineral froth may overflow into alaunder, and the gangue particles and middling may descend into the mainbody of the tank through .the opening 15, to' be again and again ,actedupon by the ascending-atomized gas, until finally, the material will beeliminated from the tank either as mineral froth, through the overflow12,01 through the gangue and liquid overflow 4, or underflow 5.

If the atomizers are tobe positioned fairly close to one another, thearrangement 7 sands settle, it is-not probable that the sand canobstruct the gas outlet so that no gas will flow when the gas pressureis turned on, and once the gas begins to flow, all ob,- structing sandsin the liquid discharge passages are quickly removed.

, 'In the flotation treatment of ores, it is desirable to have thecommunicating passages between the various compartments fairly low inthe tank, as shown in Figs. 2 and 3. This serves two useful purposes:the sands are more easily advanced from one compartment to the next; anda mineral particle, once floated, will have to descend against theascending atomized gas in order to escape. In this way theentirely'barren I gangue is quickly worked through the ap paratus,.while the mineral particles which are not readily floated, are also notreadily eliminated, and can be given a thorough treatment.

Referring to Fig. ,13; the tank is made with offsets corresponding withthe vertical partitions 2 which divides the tank into sections, and aseries of atomizers projected through these offsets in the bottom of thetank. Thestream of gas and liquid ejected from the atomizers sweepthebottom of the tank, so' that the heavier gangue matter is readilymoved toward the outlet and eliminated. The mineral is floated towardthe surface,.and before any particle of mineral, once floated. canescape, it will have to descend against the ascending atomized gas. Thebaffles 35 are intended to confine and distribute the gas in the lowerregion of the tank so as to prevent surging at the surface, and also tomove the heavier particles of gangue through the tank. Fig. 14 shows thecorrespondinghorizontal section of one end of the tank, showing theseries of atom izers arran ed so as to give a horizontal distribution ofthe gas in thelower portion of the tank. The arrangement of theatomizers is shown in detail in Fig. 15; It is preferred'to attach theoutside member, or casting 3D to the tank, as shown. This casting 30' ismade so that a pipe, or nozzle 5 may be inserted into it from the outs1e. V

Fig. 16 shows the applicationof'thein-v vention to around tank. Theatomize'rs 30" are arranged about the periphery of the tank, in thelower portion, and preferably very close to the bottom. The intersectingjets of gas and liquid give a good distribution and atomization of thegas. The lower arms 39, rotated by the shaft 38, work the heavier sandstoward the outlet 41. The

upper arms 40, skim the mineral froth from the top of the liquid. Theliquid level is maintained by the weir overflow 4. 3 It will ordinarilybe desirable to have a number of these tanks in series for effectiveflotation. I

In the modification shown in Fig. 17, the gas is applied under pressureto a continuous flow of liquid under pressure through the apparatus.This modification is particularly effective in the oxidation orreduction of salts of the variable valent elements in solution. Forekample, the reducing action of sulphur .dioxide in the reduction offerric salts in copper leach 'solutionsis not very rapid at ordinarytemperatures and atmospheric pressure. When, however, the pressure isincreased the reduction of the ferric salts is very rapid and complete.and at elevated temperatures, even the copper may be precipitated fromsulphate solutions as theelemental metal. The application of a gas to aliquid, under pressure, is well known, but the application of the. 40gas, where both the' gas and liquid are under pressure and flowingin'continuous streams, and in which the gas, in finely subdividedparticles is forced up through the liquid under a gas pressure at thetop, appears to present newpossibilities.

Referring to the modification shown in Fig. 17, represents a tankadapted to contain the liquid and to confine a gas under pressure abovethe liquid as 50' This tank may bemade of steel for noncorrosiveliquids, and of steel' lined with lead for corrosive liquids. 62 is atower adapted to contain liquid, and the height of the liquid will bedetermined by the pressure ofgasdesired. 53 shows a gas generator, andthe-gas may be supposedto be sulphur dioxide. The gas is exhausted fromthe generator 53 through the' pipe 57 by means of the ekhauster-blower54, and 60 forced through the pipe 58, through the injectors 60 and intothe liquid in the lower portion of the ,tank. The valve 59 is supposedto be closed. The injectors may be similar to those shown in Fig. '15.The gas, ascending through the liquid against super- 61 into the lowershown by 51.

atmospheric pressure and with its reducing power greatly increased,escapes at the top of the liquid into the gas space 51 until sufficientpressure has accumulated to force it through the column ofliquid in thetower 62. "The valve 59 being closed, the gas, under pressure, is forcedthrough the pipe portion of the tower 62, and escapes through the liquidin the tower at a pressure corresponding to the height of the liquid,into the space 63 in the upper portion of the tower. From the tower theI gas may be'exhausted by the exhausterblower 67 and forced underpressure into another tank 70, and so on for as many tanks as desired,until the gas is sufiiciently consumed and'the liquid sufficientlytreated. The liquid flows into the first tank through the inlet pipe 72,and from the first to the second-tank through the connecting pipe 73,and so on for. the entire series of tanks for as many tanks as desired.The liquid level may-be maintained in the tanks by any of the well knownmethods, such as a weir overflow in the last tank, or by closelyregulating the inflowing and outflowing streams of liquid. To compensatefor the differ-- ence in pressure which might arise due to variations inthe speed of the exhausterblowers, or to compensate for the consumptionof gas in the different tanks, valves 64 and 65 are placed at the top ofthe 'towers- 63: one of these valves is arranged to blow off excess gas,and the other is arranged to take in air or gas if the pressure fallsbe- 'low the amount desired. Manifestly, the

finely'sub-divided, or atomized gas, under these conditions, will have agreatly increased effect in oxidation, in reduction, heating, cooling,etc. It has been ascer tained by careful experiments, that very finelyatomized gas, even under atmospheric pressure, is from four to fivetimes as effective as gas simplybubbled in the liquid,

'or applied as in the well known Pachuca 1 tank, where the gas is simplyintroduced through an ordinary pipe and circulation ,induced through alarge central tube within the tank.

I claim:

' 1. In apparatus for treating liquid with gas, a tank adapted tocontain liquid, stationary oppositely positioned injectors in the lowerportion of the tank adapted to. inject a mixture of gas and liquid fromtheir interiors in substantially horizontal streamsinto the surroundingliquid-said injectors" having both their liquid inlets and their liquidoutlets in communication with the tank, and means for supplying gasunder pressure to said in'ectors.

2. In apparatus or treatingliquid with gas, a tank adapted to'containliquid, a plurality of stationary hollow members submerged in the liquidin the lower portion'of the tank having outwardly directed liquid gas, atank adapted to contain liquid, hollow stationary gas injectors in thelower portion of the tank adapted to receive liquid from the tank and toeject a mixture of gas and liquid from their interiors into thesurrounding liquid in the tank, said injectors being arranged so thatissuing streams of as and liquid from oppositely positioned inectorswill penetrate one another, and means for supplying gas to saidinjectors.

4. In apparatus for treating liquid with gas, a tank adapted to containliquid, a stationary injector within the tank submerged in the liquid,vertical liquid inlets communicating with the tank and with the interiorof the injector and horizontal outlets communicating with the interiorof the injector and with the tank, and means for supplying gas underpressure to the interior of the injector and ejecting it with liquidthrough the horizontal outlets into the surrounding liquid in the tank.

5. In apparatus for treating liquid with gasfa tank adaptedto containliquid, a stationary injector within'the tank submerged in the liquid, avertical liquid inlet communicating with the source of liquid supply andwith the interior of the injector, a substantially horizontal liquidoutlet communicating with the interior of the injector and with thetank, a gas supply pipe within the vertical liquid inlet adapted todeliver gas to the horizontal outlet, and means for supplying gas underpressure to said gas pipe.

6. In apparatus for treating liquid with gas, a tank adapted to containliquid, a stationary injector within the tank submerged in the liquid, aliquid inlet communicating with the source of liquid supply and with theinterior of the injector, a plurality of liquid outlets supplied withliquid through said inlet communicating with the interior of theinjector and with the tank, and means i for introducing gas underpressure into the liqpid outlets of the injector. a In apparatus'fortreating liquid with gas, a tank adapted to contain liquid, a stationaryinjector within the tank submerged in the liquid having a plurality ofoutwardly directed discharge passages communicating through a commoncenter with the source of liquid supply, means for combining a stream ofgas with a stream of liquid in the interior of the injector and ejectingthe stream-of as and liquid into the surrounding liquid in the tank, andmeans for supplying gas under pressure to the interior of the injector.

WILLIAM E. GREEN-AWALT.

